M Khan1,2,3,4,P Nag3,5, K Giuliani2,3,5,X Wang3,5, A Grivei3,5, W Hoy1,7, H Healy1,2,3,5, V Dewan1,7, G Gobe1,2,6, A Kassianos2,3,5
1NHMRC CKD CRE (CKD.QLD), University of Queensland , Brisbane,, Australia, 2Faculty of Medicine, University of Queensland, Brisbane,, Australia, 3Conjoint Internal Medicine Laboratory, Chemical Pathology, Pathology Queensland, Brisbane,, Australia, 4Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj,, Bangladesh, 5Kidney Health Service, Royal Brisbane and Women’s Hospital, Brisbane,, Australia, 6Kidney Disease Research Collaborative, Princess Alexandra Hospital and University of Queensland, Translational Research Institute, Brisbane,, Australia, 7Centre for Chronic Disease, Faculty of Medicine, University of Queensland, Brisbane,, Australia
Introduction: Chronic kidney disease (CKD) is a global health burden, increasing in incidence worldwide. Adenine diet-induced CKD is a well-accepted pre-clinical model of CKD. In vitro, adenine-induced proximal tubular epithelial cell (PTEC) injury and loss are associated with increased oxidative stress, however little is known regarding the types of cell death that cause PTEC loss. This study aimed to investigate (1) modes of cell death induced in human primary PTEC by adenine, and (2) mechanisms of cell death protection with baicalein, a novel cell death inhibitor.
Methods: Human primary PTEC were cultured with and without adenine and assessed for mitochondrial function, mitochondrial superoxides and altered cell viability by flow cytometry. Biomarkers of cell death pathways were analyzed by Western blotting. On identification of ferroptosis, the rescue of PTEC by the plant-based anti-ferroptotic flavonoid baicalein was investigated.
Result: Adenine-treated PTEC displayed significantly reduced mitochondrial function and significantly increased mitochondrial superoxides and cell death compared with untreated PTEC. Further interrogation of cell death pathways in untreated and adenine-treated PTEC revealed comparable expression of markers for apoptosis (activated caspase-3), necroptosis (pMLKL) and mitochondrial permeability transition-induced necrosis (PPIF). In contrast, the lipid repair enzyme GPX4, a biomarker for ferroptosis, was significantly reduced in adenine-treated PTEC, suggesting a pathway of ferroptototic cell death. The addition of the ferroptosis inhibitor baicalein to adenine-treated PTEC restored expression of GPX4, reduced mitochondrial superoxide, maintained levels of antioxidant enzyme superoxide dismutase 2 and reduced cell loss.
Conclusions: Our findings identify ferroptosis as a key human PTEC cell death pathway in adenine-induced CKD. The anti-ferroptotic mechanisms of baicalein indicate its antioxidant action that may eventually be translated to use in CKD patients.
I have completed a Bachelor of Pharmacy and Master of Pharmacy in Bangladesh. I am currently undertaking a PhD at the University of Queensland. During my PhD, I have established two preclinical models of chronic kidney disease and identified a plant-based bioactive compound that significantly decreases primary human proximal tubular epithelial cells (PTEC) death in these models. I have also identified the molecular mechanism/s of this PTEC death inhibition, with translational potential for therapeutic targeting in the clinic. My career objective is to elucidate the pathobiological pathways driving chronic kidney disease for pharmacological targeting using plant-based therapies.